Pond Boss Forums GENERAL QUESTIONS Help LAKE OVERFLOW RENOVATION

I have a 6.5A lake in S. Illinois with an 80A watershed. It was built in 1975 with an 18" steel pipe overflow that runs down thru the dam at a 1:5 slope. It drops approximately 20' over its 100' length. The earthen dam has a 1:3 slope on front & back with approximate 5' of free board & a virgin earth emergency spillway that has only been used once in 30 years. The main body of the lake is 10 to 15' deep & has a well developed thermocline. Much of the bank is tree lined & much of their leaves end up in the lake. We have had water quality problems the last 6 to 8 years with several low oxygen fish kills in July/August, even with lake bed airation. We were wanting to replace the steel pipe with a permament PVC siphon system that would drain the bad water from the bottom.

Upon researching all of the possible solutions we are still scratching our heads as to what will solve our problems.

1. What size siphon will we need to replace the 18" pipe with PVC?
2. If we follow the trench created by removing the old pipe we will use one 30 deg elbow, will this be too steep for efficient siphoning?
3. Do you need a trap at the bottom of the pipe? and if so what about freezing?
4. Should you put a screen on the intake?
5. What are the pros & cons of having 2 smaller pipes vs 1 larger pipe?
6. How hard is 6 to 8" pipe to work with in 20' sections? Can a do-it-yourselfer with a crew of 4-6 guys handle it?
7. What are the pros & cons of using pipe with belled ends vs joints?
8. What are the pros & cons of using 10' vs 20' lengths of pipe?
9. What type of pipe do you need? ie Schedule 40
Is there any other specifications or grades we should know about?
10. Do you need to use antiseep collars? & if so what are they made from?
11. How do you effectivley repack the clay in the trench when backfilling?
12. For manual priming do they use a normal threaded plug on tailwater end of the pipe vs a valve?
13. Is is wise to start the siphon before backfilling to check for possible leaks?
14. Do you need to anchor the pipe in the lake & if so how?
15. Does the pipe need to be joined in the trench or can you do this before & roll it into the trench?
16. To get the same water height as before at full pool, do you set the bottom of the new pipe the same level as the bottom of the old pipe?


I know that this is a big order, but after reading some of the posts on this BB I feel confident in your opinons. I have included what I consider to be most of the pertinent information about the lake without including a bunch of extraneous BS. I can send photos if need be & certainly will when the work starts.

The 1st 10 to 15 years of this lake's life it was beautiful with very good fishing & swimming. We are excited & eager to get started on this project to restore it to even better then before.

PS the name is from my Turkey Hunting fame

Welcome TOG to the PB forum. If all you want is to be able to remove bad water then there is an easy way. It involves a siphon with your current outflow/stand pipe. Take a 4in. pvc pipe and run it down the outside of the existing pipe and run it over the top of the stand pipe down inside the existing pipe to near its bottom. Put a small riser pipe (12in length with a cap) at the top of the curve over the existing pipe and a valve at the bottom on the inside which can be opened and closed by a rod which runs up to the bend. This is a siphon over the top of your existing pipe which will remove bad water from as deep as your stand pipe goes. Easy to put in and operate , low cost and no digging into the dam or having to install a full through the dam siphon.

Another option is to have an angled pipe that runs into your stand pipe at full level and down to 6 ft. That way when you have normal runoff it will be from 6 ft down until the water goes over the top of the stand pipe.

Our existing steel overflow pipe has rusted out & about 3/4 of the way down the dam is has eroded out a hole that is going to take 1-2 loads of dirt to fill up.

However we are currently running a makeshift 4" PVC siphon that we have ran down thru the existing 18" rusted out pipe. We had a major fish kill both last summer & this summer and we will be doing a rotenone renovation asap yet this fall. We are trying to reduce the volume to reduce the rotenone costs.

I think of the 16 ?'s the sizing of the pipe is what we cannot seen to get a grasp on.

TOG :

No apologies needed on my account. I understand the frustration of pipe problems and fish kill events. You did however leave out the most important fact of all, that the pipe had rusted out.

I will try to find the info on pipe size but it depends on water flow through ( rain events) in your watershed. Our coop. extension service (county agent) has access to a computer program that can provide those answers if you give them location, pond size and drainage size. Yours may have that also.

Since you are new and may not know about the search function here is some help. Three good threads on the subject and the last has a post by Burgermeister which I have copied for you and it has a link to what you may be looking for. Good luck with the renovation job.

http://www.pondboss.com/ubb/ultimatebb.php?ubb=get_topic;f=3;t=000111

http://www.pondboss.com/ubb/ultimatebb.php?ubb=get_topic;f=3;t=000110

http://www.pondboss.com/ubb/ultimatebb.php?ubb=get_topic;f=3;t=000094

burgermeister
Lunker
Member # 1766

posted July 23, 2005 11:23 AM
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Here is a guideline for siphon sizing with formulas. http://cotton.pi.csiro.au/Assets/PDFFiles/WATERpak/WPAp9_11.pdf
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Our local NRCS office personnel do not know anything about the siphon systems. They are still recommending the steel pipe thru the dam overflow systems. These systems have about a 20-25 year lifespan depending on the actual type of pipe used & will rust out leaving you just about where I am, in bad shape. This type of system in my lake has also led to the water quality problems, which can only be helped with a bottom drain/siphon system. Maybe our water problems would not have developed if we didn't have the tree lined bank or the excess depth & thermocline. The Ray Scott Small Waters tapes address lake renovations concerning this problem, by scraping dirt from the shallow upper reaches & necks to actually deepen them & placing some of the dirt in the areas that are actually too deep & not utilized by bass & most other species. They put the rest of the dirt on the back side of the dam to decrease the slope & widen the dam. This type of extensive expensive renovation is just not an option at this time.

I have not used the search funtion yet but have read a great deal of the posts on your BB. I do know that each lake is unique and that is why I listed as much information about the lake as I could on my 1st post. Sorry, that I left out the fact that the overflow pipe was rusted out. You're right, these lake problems are very frustrating & can cloud your conscience.

Thanks for the formula for siphon sizing. I have all of the measurements, but I might have to let one of my kids work the equation out for me. My 70's algebra is a bit rusty.

I would assume that after calculating this theortical flow & convert to say gal/hr or gal/24 hr we could then calculate how long it would to handle an acre-foot of water. This doesn't tell you the size of the siphon but it will give you an idea of how much water could be moved by the siphon vs my rusted our steel overflow pipe. I have seen the lake come up 2-3 feet usually only after a 5-6 inch rainy spell.

I also read the 3 threads you gave me. I am a bit apprehensive about the actual joining of the pipes. If I have to have 2 cats to push them together, I don't know. I am going on the assumption that we will end up with an 8" PVC siphon made with 20' lengths of schedule 40 with belled ends. We will have 4-5 adult men & 2 small Kubota tractors with front end loaders.

I hope to post some pictures in the near future. This should make my situation easier to visualize.

Our window of opportunity is coming right up. We hope to have a trackhoe dig it out & replace the rusted out pipe with the PVC starting on the same day. Notice I said "starting". We can take our time as the lake is down about 8' on its way to a complete draining & rotenone treatment. Right before they begin to dig up the pipe we will have to disassemble the 4" PVC siphon we have running down thru it & reassemble it in another spot to finish the draw down.

Sounds pretty simple, but everything I do turns into more work than I can every anticipate.

Has anyone had any experince using 6" belled end pvc with rubber seals? How hard is it to press together? One of the threads reported using 2 cats to push them together. We are going to end up with 2-6" siphons vs 1-8" siphon. We are afraid we cannot handle the 8", plus the 2-6's should give us a little more flow.

My main overflow pipe is 8" belled PVC with rubber seals. We put one end against a very heavy concrete drain box and pushed the pieces in the other end with a large trackhoe.

6" has got to be a little easier, but I doubt you assemble it by hand. A medium sized tractor might be enough (guess).

ewest,
I never I thought I was visually challenged but am having a hard time trying to imagine the siphon setup. Do you know of any pictures or drawings of it on the internet? How do you start the siphon?

Close the valve at the bottom of the siphon pipe inside the stand pipe , take off the cap at the top of the bend, fill with water , put the cap back on and open the valve.


l --- riser
^ --- U bend
/- \ --- top of stand pipe
l- l -- water level
l- l
l- l ---- inside stand pipe
l- l
l- l
l- l
- l
- l
- ^ ----- valve
-
- -----------outer pipe wall

This link may help to visualize and/or understand, albeit a somewhat crude system.
Siphoning a pond, step by step

Thank you ewest and Brettski. No I get it.

Theo:

This is the kind of info I have been looking for, although not quite what I wanted to hear. We are leaning towards 2-6" vs 1-8" just due to the degree of difficulty of joining the pipes. On the other hand the 8" pipe would have one-half the number of total joints for potential leaks. From the other posts I have learned to make sure the male ends are beveled & to use a lubricant & no glue. I was wondering how the rubber seals work in a system with negative pressure. I have been told that it is the positive pressure which makes the seals seal. All of the pipe on the front side should be under a negative pressure. If any of the joints out of the water on the front side were to leak, you would have no siphon. The only way 1-8" or 2-6" pipes could replace our 18" rusted out steel pipe is with full syphonic (I just make this word up) flow.

We have also decided to use adapters & screw in plugs on the bottom just down from a trap. Valves just don't seem to be worth the cost. We will use a 2" line for a priming port/siphon vent set up, similiar to the one shown on the www.ponddampiping.com site. We will fit the 2" line with a fitting that will accomodate a 2" trash pump. We will put a 2" ball valve on this line for an emercency siphon break for safety sake. This should pretty fix us up for self-priming & manual priming. We are going to used the trash guards from ponddampiping also, on the intakes top prevent sucking anything too big into the system.

I will try to post some pics as the work progresses but I am having trouble in figuring out actually how to post these. Probably need to get the kids help again. I actually might start a small website to keep my biologist friends at the National Wild Turkey Federation updated on the work.

TOG,
Good pic posting guidance is within the "Common Pond Q&A" (archives) section. You're right...get the kids involved...it's a "family thing".
E-pipe connections is another very good source for options in piping. Their inventory is EXTENSIVE. They also have technical assistance available for the questions that you need answered. I have used them and been very satisfied with the service and product. You can get most of their pricing online as you fill a cart. You have to mess around with the quantities of an item once it is in the cart....they offer quantity discounts, and it doesn't always mean alot of volume to get there.

T1G:

WRT leaks, in 5 years I haven't had any indications of leakage - no wet spots or sinkholes.

But then this is just a drain line, empty most of the time.

Tom:

You are actually not very far from me and would be welcome to come look at how mine is set up. We used 20' sections of 8" PVC with belled ends and rubber seals inside. We used the normal lubricant they use for water lines, but I've heard that dishwashing soap and other stuff works also.

As to how hard it is to join two sections, it isn't that easy, but it isn't that bad. The first few are the toughest. Initially, we put one end against a vehicle tire and used a big metal bar (what the rural water companies use) to pry against the other end and join them together. As we added more sections, all we had to use was the metal bar. One kinda macho guy could do it; but it works better with two.

To join sections of the 14" pipe, we doused the ends with liberal amounts of some lubricant (can't remember if soap, oil, or what) and used the 4-wheeler winch. Went together real easy once lubricated.

The big issue that concerns me is freezing. I'd put a permanent one in place if I was confident it could handle the ice.

Jeff

Ours will be permanent. We currently have a make shift 4" siphon running down thru the metal rusted out pipe, just to get the lake down low enough that we don't have to worry about a big storm bringing the water level up into our excavation. The other night a town about 30 miles north of us got a 7" rain, while we got .2".
We are pretty much weekenders & hope to dig out(with the help of a medium sized trackhoe) the old 18" pipe this weekend & reshape the trench with fill dirt. We will move the 4" siphon about 10' over to one side & restart it. This time we will have to add quite a bit more pipe as it will have to run up & over the entire dam.

The following weekend we will join the pipe sections & bury it & fire them up. The 2 permament 6" & the make shift 4" should get the lake down to the max so we can use rotenone by mid Sept & restock in Oct. We will have to keep adding onto the front side of the 4" pipe as we go to get rid of all but about 3 acre-feet of water.

The only concern we have about freezing is the trap at the end on the backside. We are thinking about putting it in below the frost line & see what happens. We do not have a trap in the 4" siphon & it quits about every 2 days from sucking air in the bottom. I guess the traps are essential to get 100% siphonic flow. We were also wondering if we need some type of varmint screen on the end for when the water is not flowing. We have otter, beaver & muskrats in our area, as our tailwaters are only 200 yds from the Skillet Fork river.

Here is a pic of the siphon. It is 8in. and the big pipe is 1in steel pipe with a 54in dia.( I think) It has ladder steps welded down the inside . Going down inside the pipe to fool with the valve is an experience.